def a174(x):

    return "Yes" if x >= 30 else "No"

def main():
    x = int(input())
    print(a174(x))

if __name__ == '__main__':
    main() def a174(x):

    return "Yes" if x >= 30 else "No" a174 return "Yes" if x >= 30 else "No" "Yes" if x >= 30 else "No" x >= 30 x 30 "Yes" "No" x x def main():
    x = int(input())
    print(a174(x)) main x = int(input()) x int(input()) int input() input print(a174(x)) print a174(x) a174 x if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def a174(x):

    return "Yes" if x >= 30 else "No" def a174(x):

    return "Yes" if x >= 30 else "No" a174 def main():
    x = int(input())
    print(a174(x)) def main():
    x = int(input())
    print(a174(x)) main
def a174(x):

    return "Yes" if x >= 30 else "No"

def main():
    x = int(input())
    print(a174(x))

if __name__ == '__main__':
    main()